If a mouse falls into olive oil or the like, the mouse and the part surrounding are to be thrown away. This is based on the Hadith
recorded in the Sahih (authentic book of Sunnah) of
The Messenger of Allah (peace be upon him) was asked regarding ghee (cooking butter) in which a mouse had fallen. He (peace be upon him) said: Take out the mouse and throw away the ghee around it and use the rest.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.